I want to know what those of you who have been roasting a while wish their roaster could do?

In general why I'm asking:I'm about to start building a custom roaster with the intention of pushing the limit as to just how good I can dial things in for a bean. I've got a rough design and want to make sure I'm addressing everything possible in advance. Right now I'm putting together the equipment for a gas hot air roaster and all of my experience to date is electric drum. I work in a custom fab shop so a lot of things are possible. Thanks in advance.

Some options you might consider for your glass column if you try to build a roaster along the lines of Oldgearhead's, might be to try and locate a used or salvageable I-Roast for the glass chamber. Of course it isn't very tall, only about 3.5 inches and the diameter is just under 4.5 inches. Although the height is limited, it could be part of a stainless steel tube roast chamber with the glass as the viewing area. As long as the beans are visible during roasting in some part of the roast chamber, then you'll probably be happy with your design results. Another option for a glass column is a pyrex chimney from a Coleman type lantern. I've seen smaller ones in sporting goods stores similar to the I-Roast chamber, and some of the larger ones also, still available on Ebait.

Another option might be to design and construct a segmented glass tube using ceramic glass, This is the type of glass used for woodstove glass doors, even stronger and more heat resistant than pyrex glass. Pyrex glass or even tempered glass may be an option for this design because of lower cost, since it's probably unlikely you'll ever get up to the temps that a wood fire would produce in a wood stove requiring the ceramic glass for heat resistance and strength. I've had all three types installed in my fireplace glass doors and the pyrex and tempered do take a lot of heat to destroy them, probably more than you'll see with 500 degree temps in a roaster.

Because you mentioned 'blower motor' I assume you are planning a fluid-bed roaster. Is that correct? There are other choices to make:1) How large will your loads be? - This determines about everything, heat source, blower size, roast chamber size, amount of chaff to deal with, etc, etc.Note - The Corning/Pyrex 'Bake-A-Round' makes a nice roast chamber for up to 500 grams.

2) Blower/Vacuum units - Most of these are made by Ametek/Lamb and are available about 3 diameters. The most powerful are the 7" designed for 'whole-house' vacuum sources. The most popular are the 5.7" (145 mm) units they are available in single-stage, dual-stage, single-speed or two-speed, thru-flow or tangential discharge, and with or without separate intake for the motor brushes. The simplest of these the 5.7" two-stage, thru-flow, will easily loft 750 grams of green beans if the RC and base are properly designed. Controlling the speed of your vacuum motor will probably be necessary. If your motor is an AC/DC (Universal, They have brushes), you can use a variable auto-transformer, light-dimmer, router-controller, or DC drive for control. Most 5.7" units are AC/DC, some 'whole-house' units are not.

I want to know what those of you who have been roasting a while wish their roaster could do?

In general why I'm asking:I'm about to start building a custom roaster with the intention of pushing the limit as to just how good I can dial things in for a bean. I've got a rough design and want to make sure I'm addressing everything possible in advance. Right now I'm putting together the equipment for a gas hot air roaster and all of my experience to date is electric drum. I work in a custom fab shop so a lot of things are possible. Thanks in advance.

To repeat what OGH referenced, an important variable that you are not mentioning is how many pounds (or ounces) of beans do you wish to roast at one time? That one variable affects many others in a big way. Please let us know.

Len

"Coffee leads men to trifle away their time, scald their chops, and spend their money, all for a little base, black, thick, nasty, bitter, stinking nauseous puddle water." ~The Women's Petition Against Coffee, 1674

I think for my first build the capacity will be 1lb / roast. It will most likely be a fluid-bed. I was working on ideas to move the beans with a lower air flow for a higher efficiency and just to be different, but I'm thinking it's a good idea to at least start with a common method that works for the first attempt. Plus it's really cool to watch the beans in a fluid-bed.

Those were some great ideas for the glass. I'm looking for a good price on the "bake-a-round" and will likely buy one to play with. Another thought was to use a vertical strip of glass as a view window and fabricating the chamber out of metal. It would give me total control over size and shape. Are there any benefits you know of by tapering the cylinder at the base?

Another thought was measuring the temperature of the beans as isolated from the hot air flow as possible. Like right up against the wall of the tube where the beans are returning to the base. Has anyone played with temperature probe location?

Another thought was measuring the temperature of the beans as isolated from the hot air flow as possible. Like right up against the wall of the tube where the beans are returning to the base. Has anyone played with temperature probe location?

I started roasting three year ago with a roaster that was so loud I could not hear the 'cracks' (a highly modified Zach & Danni). So I fashioned a BMT (Bean Mass Temperature) probe that worked very well. In fact, if one kept a careful eye on RoR (Rate of Rise) the exothermic point could be pinpointed. I believe it was because the Z&D is a convection roaster, but it's is not a fluid-bed.

When I built my electric, fluid-bed, one-pound, heat-recycling, roaster, I found that by placing the probe as you describe in the return bean path I could get a reliable BMT reading (400ºF at first crack with most 'hard' beans). However, it could not detect exothermic activity. I also found that a probe located right under my perf plate also tracked the BMT and with a few modifications I was able the hear the 'cracks' with my new roaster. So I don't even use the BMT anymore. I think hearing the cracks is more important than BMT with a fluid-bed roaster. This is especially true with decaf and going from 'wet' processed to 'natural' processed beans. What would be very nice, but expensive, would be an industrial IR probe looking right at a bean during a roast. But remember IR can't see through glass, and the temperatures, inside, at the very top of a glass RC are 250-350ºF+.

I would not recommend messing with a low air flow design. When I built the bubblebed prototype this was one of the supposed benefits but the issue is that throughout the roast the beans change weight, shape and have different airflow requirements. As you adjust airflow, you change the heat being transferred. Then when you readjust the heat, that changes the expansion of the aair that changes the airflow. It's a PITA to constantly adjust and readjust. Keep it simple with a standard airflow rate and just make sure your burner has enough BTU to satisfy it.

As for proble location you want it as far out of the hot air stream as possible in the return bean path.

I've got a pyrex tube that's not being used, but it's way too big for 1#.

Air Flow - As far as I know there are only two convection coffee roasters that rely on low air flow: The GeneCafe' and the Nesco. They are able to use low air flow because they stir the beans mechanically. Fluid-bed roasters work fine as long as the bean mass is fluid. I adjust my flow rate four times during each roast:1) Start2) T = 3:003) T = 6:004) Cooling

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